Both are scheduled for bond hearings Friday. Police say it's unclear if they have attorneys.
The blaze gutted the two-story, five-apartment building. A man and woman, their two children, the woman's 16-year-old twin siblings and a friend were killed.
Police Supt. Lori Lelis tells the Chicago Tribune that Myers owned the building, was having problems with the Internal Revenue Service and told Comier to "take care of the building."
